SG6846ACSZ

Product Specification Highly Integrated Green-Mode PWM Controller SG6846A consumption, a proprietary green-mode function provides off-time modulation to continuously decrease the switching frequency under light-load conditions. Under zero-load conditions, the power supply enters burst-mode. The SG6846A is especially designed for SMPS with surge-current output, incorporated with a two-level OCP function. Besides the cycle-by-cycle current limiting, if the switching current is higher than two thirds the peak-current threshold for 1700ms, over-current protection is activated and the SG6846A latches off. If the switching current is higher than two thirds the peak-current threshold for 100ms and the voltage on the VDD pin is higher than VDD-OFF + 1V, the PWM pulses are latched off immediately once VDD voltage is lower than VDD-OFF + 1V; useful if an output short-circuit occurs. SG6846A also integrates a frequency hopping function that reduces EMI emission of a power supply with minimum line filters. Its built-in synchronized slope compensation provides proprietary internal compensation for constant output power limit over a universal AC input range. Also, the gate output is clamped at 18V to protect the external MOSFET from over-voltage damage. Internal soft-start is built-in to reduce stress on the MOSFET and start-up current during power-on period. Other protection functions include: AC input brownout protection with hysteresis, VDD over-voltage protection, and over-temperature protection. For over-temperature protection, an external NTC thermistor can be applied to sense the ambient temperature. When OCP, VDD OVP, or OTP are activated, an internal latch circuit is used to latch-off the controller. The PWM pulses stay latched off until the power supply is unplugged from the main outlet. SG6846A is available in an 8-pin SOP package. FEATURES Two-level OCP with 1700ms delay time Output short-circuited delay time: 100ms Low start-up current (8µA) Low operating current (3.7mA) Peak-current mode operation with cycle-by-cycle current limiting Programmable PWM frequency with frequency hopping PWM frequency continuously decreasing with burst mode at light loads VDD over-voltage protection (OVP) AC input brownout protection with hysteresis and constant output power limit Constant output power limit (full AC input range) Internal latch circuit for OVP, OTP, and OCP Built-in soft-start Open-loop protection with 1700ms delay time APPLICATIONS General-purpose switch-mode power flyback power converters, including: Power adapters Open-frame SMPS Specifically fit for SMPS with surge-current output (such as for printers, scanners, motor drivers, etc.) supplies and DESCRIPTION The highly integrated SG6846A series of PWM controllers provides features to enhance the performance of flyback converters. To minimize standby power TYPICAL APPLICATION © System General Corp. Version 1.1.1 (IAO33.0059.B1) -1- www.sg.com.tw • www.fairchildsemi.com September 26, 2007 Product Specification Highly Integrated Green-Mode PWM Controller SG6846A PIN CONFIGURATION MARKING DIAGRAMS F: L=OCP Latch, C=OCP auto-recovery T: S=SOP P : Z=Lead Free Null=regular package XXXXXXXX: Wafer Lot Y: Year; WW: Week V: Assembly Location GND FB VIN RI GATE VDD SENSE RT SG6846AFTP XXXXXXXXYWWV ORDERING INFORMATION Part Number SG6846ALSZ SG6846ACSZ (Preliminary) OCP Latch Yes No Pb-Free Package 8-Pin SOP 8-Pin SOP PIN DESCRIPTIONS Pin No. Symbol 1 2 GND FB Function Ground Feedback Line-voltage Detection Reference Setting Temperature Detection Description Ground. The signal from the external compensation circuit is fed into this pin. The PWM duty cycle is determined in response to the signal from this pin and the current-sense signal from Pin 6. Line-voltage detection. The line-voltage detection is used for brownout protection with hysteresis. Constant output power limit over a universal AC input range is also achieved using this VIN pin. Consider adding a low-pass filter to filter out line ripple on the bulk capacitor. A resistor from the RI pin to ground generates a reference current source that determines the switching frequency. Increasing the resistance reduces the switching frequency. Using a 26kΩ resistor results in a 65kHz switching frequency. For over-temperature protection, an external NTC thermistor is connected from this pin to the GND pin. The impedance of the NTC decreases at high temperatures. Once the voltage of the RT pin drops below a threshold, PWM output is disabled. 3 VIN 4 RI 5 RT 6 SENSE Current sense. The sensed voltage is used for peak-current-mode control and cycle-by-cycle current limiting. If the switching current is higher than two thirds of the peak-current threshold for longer than 100ms and VDD is higher than 12V and lasts for 1700ms, over-current Current Sense protection is activated. If an output short over-current also occurs and lasts for 100ms and VAUX is lower than 12V, SG6846A turns off immediately. This two-level OCP feature is especially suitable for SMPS with surge current output. It also has built-in 5ms soft-start time as switching frequency operates at 65KHz. Power Supply Driver Output Power supply. If an open-circuit failure occurs in the feedback loop, the internal protection circuit disables PWM output as long as VDD exceeds the threshold. The totem-pole output driver for the power MOSFET, internally clamped below 18V. 7 8 VDD GATE © System General Corp. Version 1.1.1 (IAO33.0059.B1) -2- www.sg.com.tw • www.fairchildsemi.com September 26, 2007 Product Specification Highly Integrated Green-Mode PWM Controller SG6846A BLOCK DIAGRAM © System General Corp. Version 1.1.1 (IAO33.0059.B1) -3- www.sg.com.tw • www.fairchildsemi.com September 26, 2007 Product Specification Highly Integrated Green-Mode PWM Controller SG6846A ABSOLUTE MAXIMUM RATINGS Symbol VVDD VL PD RΘJC TJ TSTG TL ESD Parameter Supply Voltage Input Voltage to VIN, FB, SENSE Pins Power Dissipation Thermal Resistance (Junction-to-Case) Operating Junction Temperature Storage Temperature Range Lead Temperature (Wave Soldering or Infrared, 10 Seconds) Electrostatic Discharge Capability, Human Body Model Electrostatic Discharge Capability, Machine Model Value 25 -0.3 to 7.0 400 54.4 -40 to +125 -65 to +150 260 5.0 200 Unit V V mW °C/W °C °C °C kV V * All voltage values, except differential voltages, are given with respect to GND pin. * Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. RECOMMENDED OPERATING JUNCTION TEMPERATURE Symbol TA Parameter Operating Ambient temperature Value -20°C ~ 85°C Unit V *For proper operation ELECTRICAL CHARACTERISTICS VDD=15V, TA=25°C, unless otherwise noted. VDD SECTION Symbol Parameter VDD-OP VDD-ON VDD-OFF IDD-ST IDD-OP VDD-OVP tD-VDDOVP IDD-OVP VDD-SCP Continuously Operating Voltage Turn-on Threshold Voltage Turn-off Voltage Start-Up Current Operating Supply Current VDD Over-Voltage Protection (Latch off) VDD OVP Debounce Time VDD OVP Latch-up Holding Current Threshold Voltage on VDD for Short-Circuit Protection RI=26KΩ VDD=5V VCS>VSTH lasts for TDELAY-Short VDD-ON – 0.16V GATE open 22.6 23.6 100 70 15.5 9.5 16.5 10.5 Test Condition Min. Typ. Max. 20 17.5 11.5 30 5 24.6 Unit V V V µA mA V µs µA VDD-OFF + 0.5V VDD-OFF + 1V VDD-OFF + 1.5V V VIN SECTION Symbol VIN-OFF VIN-ON Parameter PWM Turn-off Threshold Voltage PWM Turn-on Threshold Voltage Min. 0.65 VIN-OFF+0.18 Typ. 0.70 VIN-OFF+0.2 Max. 0.75 VIN-OFF+0.22 Unit V V © System General Corp. Version 1.1.1 (IAO33.0059.B1) -4- www.sg.com.tw • www.fairchildsemi.com September 26, 2007 Product Specification Highly Integrated Green-Mode PWM Controller SG6846A FEEDBACK INPUT SECTION Symbol Parameter AV ZFB VFB-OPEN VFB-OLP tD-OLP Input Voltage to Current-Sense Attenuation Input Impedance FB Pin Open Voltage FB Open-Loop Trigger Level Delay Time of FB Pin Open-Loop Protection RI=26KΩ 5.6 4.7 1600 Test Condition At Green Mode Min. Typ. 1/4 5.5 6.2 5.2 1700 Max. Unit V/V kΩ 6.6 5.7 1800 V V ms CURRENT-SENSE SECTION Symbol Parameter ZSENSE tPD tLEB VSTH1V VSTH3V VSTH1V-2/3 VSTH3V-2/3 tD-OCP VSLOPE tD-Short tSS-65KHz tSS-130KHz Input Impedance Delay to Output Leading-Edge Blanking Time Threshold Voltage for Current Limit Threshold Voltage for Current Limit 2/3 Threshold Voltage for Current Limit 2/3 Threshold Voltage for Current Limit *Delay Time for Over-Current Protection Slope Compensation *Output Short Delay Time Soft-Start Time Soft-Start Time VIN=1V VIN=3V VIN=1V VIN=3V RI=26KΩ Duty=DCYMAX VCS> VSTH, RI=26KΩ RI=26KΩ RI=13KΩ 92 0.58 0.48 1500 270 360 0.83 0.70 0.61 0.51 1600 0.33 100 5 2.5 108 0.64 0.54 1700 Test Condition Min. Typ. 12 Max. 250 Unit kΩ ns ns V V V V ms V ms ms ms OSCILLATOR SECTION Symbol Parameter FOSC FOSC,MAX FOSC,MIN thop-1 FOSC-G VFB-N VFB-G SG FDV FDT Normal PWM Frequency Maximum PWM Frequency Minimum PWM Frequency Jitter Period Green-Mode Minimum Frequency FB Pin Frequency Reduction Threshold FB Voltage at FOSC-GREEN Slope for Green-Mode Modulation Frequency Variation vs. VDD Deviation Frequency Variation vs. Temperature Deviation Pin, FB Voltage Jitter Range Pin, FB Voltage Jitter Range Center Frequency Jitter Range Center Frequency Jitter Range Center Frequency Jitter Range Test Condition RI=26KΩ, VFB>VN RI=13KΩ, VFB>VN RI=36KΩ, VFB>VN RI=26KΩ, VFB>VN RI=26KΩ RI=26KΩ, VFB=VN RI=26KΩ, VFB=VG RI=26KΩ VDD=11.5V to 20V TA=-20 to 85 °C Min. 62 124 44.8 Typ. 65 ±4.2 130 ±8.4 47.0 ±2.9 4.4 Max. 68 136 49.2 Unit kHz kHz kHz ms 18.0 22.5 2.1 4.2 1.6 1.45 85 25.0 kHz V KHz V KHz Hz/mV 5 1.5 5.0 % % © System General Corp. Version 1.1.1 (IAO33.0059.B1) -5- www.sg.com.tw • www.fairchildsemi.com September 26, 2007 Product Specification Highly Integrated Green-Mode PWM Controller SG6846A Frequency +4.2KHz 65kHz -4.2KHz PWM Frequency +1.45KHz 22.5kHz -1.45KHz V FB-G V FB-N VFB PWM OUTPUT SECTION Symbol DCYMAX VGATE-L VGATE-H tR tF VGATE-CLAMP Parameter Maximum Duty Cycle Output Voltage Low Output Voltage High Rising Time Falling Time Gate Output Clamping Voltage Test Condition VDD=15V, IO=50mA VDD=12V, IO=50mA GATE=1nF GATE=1nF VDD=20V Min. Typ. Max. 90 1.5 Unit % V V ns ns 8 350 50 18 V OVER-TEMPERATURE PROTECTION SECTION Symbol IRT VRTTH tD-OTP Parameter Output Current of RT Pin Threshold Voltage for Over-Temperature Protection Over-Temperature Latch-Off Debounce Test Condition RI=26KΩ Min. 64 1.015 Typ. 70 1.065 100 Max. 76 1.115 Unit µA V ms RI=26KΩ RI SECTION Symbol RINOR Parameter RI Operating Range Test Condition Min. 13 Typ. Max. 36 Unit kΩ © System General Corp. Version 1.1.1 (IAO33.0059.B1) -6- www.sg.com.tw • www.fairchildsemi.com September 26, 2007 Product Specification Highly Integrated Green-Mode PWM Controller SG6846A TYPICAL CHARACTERISTICS Turn-on Threshold Voltage (VDD-ON) vs Temperature 20 18 VDD-ON (V) 16 14 12 10 -40 -25 -10 5 20 35 50 65 80 95 110 125 11.5 11.1 VDD-OFF (V) 10.7 10.3 9.9 9.5 -40 -25 -10 5 20 35 50 65 80 95 110 125 Temperature (℃) Turn-off Voltage (VDD-OFF) vs Temperature Temperature (℃) Start-Up Current (IDD-ST) vs Temperature Start-Up Current vs VDD Voltage 30.0 26.8 10 8 IDD-ST (uA) 23.6 20.4 17.2 14.0 -40 -25 -10 5 20 35 50 65 80 95 110 125 IDD-ST (uA) 6 4 2 0 10 11 12 13 14 15 16 Temperature (℃ ) VDD (V) PWM Turn-off Threshold Voltage (VIN-OFF) vs Temperature PWM Turn-on Threshold Voltage (VIN-ON) vs Temperature 2.5 1.00 2.0 0.98 VIN-OFF (V) 1.5 VIN-ON (V) 0.96 1.0 0.94 0.5 0.92 0.0 -40 -24 -7 10 26 43 59 76 92 109 125 0.90 -40 -25 -10 5 20 35 50 65 80 95 110 125 Temperature (℃ ) Temperature (℃ ) © System General Corp. Version 1.1.1 (IAO33.0059.B1) -7- www.sg.com.tw • www.fairchildsemi.com September 26, 2007 Product Specification Highly Integrated Green-Mode PWM Controller Normal PWM Frequency (F OSC ) vs Temperature PWM Frequency vs FB Voltage SG6846A 68 70 67 PWM Frequency (kHz -40 -25 -10 5 20 35 50 65 80 95 110 125 56 F OSC (kHz) 66 42 64 28 63 14 62 0 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 Temperature (℃ ) VFB (V) Current - limit Threshold vs Vin Voltage 2/ Current - limit Threshold vs Vin Voltage 3 0.90 0.85 0.80 0.75 0.70 0.65 0.60 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 0.90 0.82 VTH-O (V) VTH-P (V) 0.74 0.66 0.58 0.50 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 VIN ( V ) VIN (V) Output Current of RT Pin (I ) vs Temperature RT FB Output High Voltage (VRTTH) vs Temperature 71.0 1.4 70.5 1.2 70.0 VRTTH (V) IRT (uA) 1.0 69.5 0.8 69.0 0.6 68.5 -40 -25 -10 5 20 35 50 65 80 95 110 125 0.4 -40 -25 -10 5 20 35 50 65 80 95 110 125 Temperature (℃ ) Temperature (℃ ) © System General Corp. Version 1.1.1 (IAO33.0059.B1) -8- www.sg.com.tw • www.fairchildsemi.com September 26, 2007 Product Specification Highly Integrated Green-Mode PWM Controller SG6846A OPERATION DESCRIPTION Start-up Operation The turn-on/turn-off thresholds are fixed internally at 16.5V/10.5V. To enable the SG6846A during start-up, the hold-up capacitor must first be charged to 16.5V through the start-up resistor. The hold-up capacitor continues to supply VDD before energy can be delivered from the auxiliary winding of the main transformer. The VDD must not drop below 10.5V during this start-up process. This UVLO hysteresis window ensures that the hold-up capacitor can adequately supply VDD during start-up. The typical start-up current is only 8µA, which allows a high-resistance, low-wattage start-up resistor to minimize power loss. A 1.5MΩ/0.25W start-up resistor and a 10µF/25V VDD hold-up capacitor are sufficient for a universal input range. The required operating current has been reduced to 3.7mA, which enables higher efficiency and reduces the VDD hold-up capacitance requirement. corresponding 65kHz switching frequency. The relationship between RI and the switching frequency is: fPWM(kHz) = R1690 ) (kΩ I ---------------------------- (1) If an open-circuit or short-circuit to ground occurs at the RI pin, the internal protection circuit immediately shuts down the controller. Two-Level Over-Current Protection The cycle-by-cycle current limiting shuts down the PWM immediately when the switching current is over the peak-current threshold. Additionally, when the switching current is higher than two thirds the peak-current threshold, the internal counter counts down. When the total accumulated counting time is more than around 1600ms (RI=26kΩ), the controller is latched off the internal counter counting up. When the switching current is lower than two thirds of the peak current threshold, the internal counter counts down. When the total accumulated counting time is more than about 1700ms (RI=26kΩ), the controller is latched off. This two-level OCP protection and up/down counter are especially designed for SMPS with surge current for printers, scanners, motor drivers, etc. Green-Mode Operation The proprietary green-mode function provides off-time modulation to continuously decrease the switching frequency under light-load conditions. Maximum on-time is limited to provide protection against abnormal conditions. To further reduce power consumption under zero-load condition, the PWM oscillator is completely turned off and the power supply enters burst-mode. This green-mode function dramatically reduces power consumption under light-load and zero-load conditions. Power supplies using the SG6846A can meet even the most restrictive international regulations regarding standby power consumption. Constant Output Power Limit For constant output power limit over a universal input-voltage range, the peak-current threshold is adjusted by the voltage of the VIN pin. Since the VIN pin is connected to the rectified AC input line voltage through the resistive divider, a higher line voltage generates a higher VIN voltage. The threshold voltage decreases as the VIN voltage increases, making the maximum output power at high-line input voltage equal to that at low-line input. Oscillator Operation A resistor connected from the RI pin to GND generates a reference current source used to determine the PWM frequency. Increasing the resistance decreases the amplitude of the current source and reduces the PWM frequency. Using a 26kΩ resistor results in a © System General Corp. Version 1.1.1 (IAO33.0059.B1) -9- www.sg.com.tw • www.fairchildsemi.com September 26, 2007 Product Specification Highly Integrated Green-Mode PWM Controller SG6846A Brownout Protection Since the VIN pin is connected through a resistive divider to the rectified AC input line voltage, it can also be used for brownout protection. If the VIN voltage is less than 0.7V, the PWM output shuts off. If the VIN voltage is over 0.9V, the PWM output turns on again. The hysteresis window for ON/OFF is around 0.2V. VDD Over-voltage Protection VDD over-voltage protection is built-in to prevent the controller from over-voltage destruction. When VDD voltage is over 23.6V, the SG6846A is latched off. Noise Immunity Noise from the current sense or the control signal may cause significant pulse jitter, particularly in continuous-conduction mode. Slope compensation helps alleviate this problem. Good placement and layout practices should be followed. Avoid long PCB traces and component leads. Compensation and filter components should be located near the SG6846A. Usually an RC network is put on between sensing resistor and the CS pin to filter high-frequency switching noise, as shown Figure 1. Over-Temperature Protection An external NTC thermistor can be connected from the RT pin to GND. The impedance of the NTC decreases at high temperatures. When the voltage of the RT pin drops below 1.065V, the SG6846A is turned off. For the protection modes options, please see ORDER INFORMATION. FIG-1 Current Sense RC Filter © System General Corp. Version 1.1.1 (IAO33.0059.B1) - 10 - www.sg.com.tw • www.fairchildsemi.com September 26, 2007 Product Specification Highly Integrated Green-Mode PWM Controller SG6846A REFERENCE CIRCUIT Application Circuit for 32V/16V Output P1 t F1 RT1 2 4 3 VZ1 P2 P7 LF1 CY2 3 1 1 CY1 CX1LF2 4 BD1 1 2 5 TX1 13 + R16 D4 1 2 2 3 10 2 2 R8 3 1 C2 R12 C4 1 6 + 2 CX2 4 P32V P32V L1 C12 2 C16+ 1 + 32V C13 32V 1 R1 R2 R3 2 R9 1 + C11 R17 P16V P16V L2 C17+ 2 + 3 11 1 2 3 D1 21 2 L4 12 D3 2 1 D2 2 7 1 9 2 2 1 R4 1 C3 C5 1 + R11 C14 + 16V 16V C15 D5 1 1 P32V U1 1 GND FB VIN RI GATE VDD SENSE RT 8 7 6 5 2 R13 R6 R10 NTC1 C6 Q1 1 2 FB 2 2 3 L3 R14 P16V C1 1 + R5 4 R7 1 3 P16V R15 4 FB 1 FB P16V C7 U2 3 2 C9 K R P16V R18 R19 R21 P32V R20 U3 A BOM PART NO. R1, R2, R3, R4 R8, R9 R5 R15 R13 R18 R21 R7 R6 R19 R14 R16, R17 R11 R12 R20 R22 VALUE 470KΩ +/-5% S1MΩ +/-1% 16K2Ω +/-1% 1K5Ω +/-5% 10Ω +/-5% 4K7Ω +/-5% 15KΩ +/-1% 27KΩ +/-5% 330Ω +/-1% 102KΩ +/-1% 0Ω22 +/-5% 1W 20Ω +/-5% 20KΩ +/-5% 100KΩ +/-5% 887KΩ +/-1% 10KΩ +/-1% PART NO. C4 C10,C11 C6,C7 C9 C14,C17 C15 C13,C16 C2 C1 C3 CX1 C8 C5 CX2 D1 D2 VALUE 103 P 630V 102 P 1KV 102 P 50V 222 P 50V 470µ 25V 220µ 25V 220µ 50V 150µ 400V 4µ7 50V 10µ 50V X1 0.47µ 275V Y2 222P 250V 100µ 50V X2 0.1µF 275V 1N4148 BYV95C PART NO. D3 BD1 D4 D5 F1 L1,L2 L4 U3 U1 U2 Q1 TX1 RT1 VZ1 VALUE FR103 1.0A 200V DBL406G BYT28-300 BYV32-150 250V4A QUICK 1.8µH 10µH TL431 +/-1% SG 6846 PC817 7NB60 EI-33 SCK053 14ψ 470V © System General Corp. Version 1.1.1 (IAO33.0059.B1) - 11 - www.sg.com.tw • www.fairchildsemi.com September 26, 2007 Product Specification Highly Integrated Green-Mode PWM Controller SG6846A PACKAGE INFORMATION8PINS-SOP(S) 8 5 C 1 b 4 e D A1 A Dimensions Millimeter Min. Typ. 1.346 0.101 0.406 0.203 4.648 3.810 1.016 5.791 0.406 0° 4.978 3.987 1.524 6.197 1.270 8° 0.183 0.150 0.040 0.228 0.016 0° Symbol A A1 b c D E e F H L θ˚ Max. 1.752 0.254 1.270 0.381X45° © System General Corp. Version 1.1.1 (IAO33.0059.B1) H F E Θ L Inch Min. 0.053 0.004 Typ. 0.016 0.008 Max. 0.069 0.010 0.050 0.015X45° 0.196 0.157 0.060 0.244 0.050 8° - 12 - www.sg.com.tw • www.fairchildsemi.com September 26, 2007 Product Specification Highly Integrated Green-Mode PWM Controller SG6846A © System General Corp. Version 1.1.1 (IAO33.0059.B1) - 13 - www.sg.com.tw • www.fairchildsemi.com September 26, 2007